When you're first startled awake in the middle of the night by a loud, gritting sound emanating from your child's room, you may have two questions: how can such a loud racket not be harmful to their teeth? And, how can they sleep through it?

While it sounds earth-shattering, teeth grinding (medically known as bruxism) is a common habit among children. It involves an involuntary grinding, clenching or rubbing of the teeth together, either during the day or during night sleep.

While certain medications or conditions could be factors, it's believed most teeth grinding arises from the immaturity of the part of the neuromuscular system that controls chewing. It's believed to trigger a night episode as the child moves from deeper to lighter stages of sleep toward waking. Older children and adults typically handle these sudden shifts without incident, but a young child's under-developed chewing response may react with grinding.

If a child's teeth are normal and healthy, teeth-grinding typically won't create any lasting damage. But because grinding does generate pressures greater than the teeth normally encounter, it can be harmful to decayed teeth or those with enamel erosion due to high acid from consumption of sports and soda drinks. And it's also a cause for concern if the habit continues into later childhood or adolescence.

To avoid these problems, it's best to keep your child's teeth as healthy as possible by practicing daily brushing and flossing, and regularly seeing a dentist for cleanings, treatments and preventive measures like topical fluoride or sealants. And be sure to limit sugar and acidic foods and drinks in their diet to protect against decay and erosion.

You can also take steps to minimize teeth grinding and its effects. Consult with your physician about any medications they're taking that might contribute to the habit. If there are psychological issues at play, seek therapy to help your child better manage their stress. Your dentist can also fashion a custom night guard worn while they sleep that will prevent their teeth from making solid contact during grinding episodes.

Most importantly, let your dentist know if your child grinds their teeth. Keeping an eye on this potentially harmful habit will help lead to appropriate actions when the time comes.